In typical industrial and manufacturing facilities, various types of machinery are employed at various stages of the production process. Such machines generally function to provide the power and moving forces necessary to achieve the end product or process. From a production viewpoint, it is desirable to maintain the machinery in good operating condition to avoid unproductive downtime and profit loss when a machine experiences a failure condition. Therefore, a typical plant maintenance program will involve activities for monitoring the operating condition of plant machinery so that the health and condition of the machines can be maintained at high levels to reduce the number of unexpected machine failures.
Portable instruments are often employed to periodically monitor various operating conditions of industrial machinery. These portable instruments, which are often referred to as data collectors or data analyzers, typically include a vibration transducer attached to what is essentially a hand-held computer. The maintenance technician places the vibration transducer against a predefined test point of the machine. The resultant machine vibration signal produced by the transducer is provided to the data collector where the data is processed and stored for later downloading to a host computer. The host computer then analyzes the vibration data for faults or other anomalous conditions.
Machines within a facility are typically monitored according to a route which is programmed into the data collector by the host computer. The route will typically include a list of machines, test points, and a set-up condition for each test point. There may be as many as thirty or more machines in the route with ten test points on each machine, and for each test point there may be specified a vibration frequency range to be analyzed, a type of analysis to be performed, a particular type or set of data to be stored, and similar other parameters. In response to commands from the user, the hand held instrument prompts the user for the identity of the machine and the test point to be monitored, and it automatically sets up the instrument, for example, to accept the specified frequency range for the test point, perform the specified analysis and store the specified type or set of data. A Fast Fourier Transform analysis may be performed on a pre-selected frequency range of the data and all or part of the resulting frequency spectrum may be stored and displayed. As the user progresses through the thirty machines and the corresponding 300 test points, he collects and stores vibration data which is subsequently transferred to the host computer for long term storage and further analysis.
The present invention provides a completely new approach to machine monitoring. Instead of manually collecting machine data with a portable device of the type described above, this invention contemplates a machine monitor which is attached directly to the machine. The monitor includes the electronics and sensors necessary to sense, analyze, and store one or more of the machine's operating characteristics, including vibration, temperature, and flux. The monitor case or enclosure is configured to minimize attenuation of machine parameters or operating characteristics (such as vibration and temperature) between the motor and sensors. Since the monitor and the machine to which it is attached are often located in harsh industrial environments, the monitor's electronics and sensors must be adequately protected from mechanical shock, thermal shock, moisture, oil, dirt, and other environmental elements in order to function reliably over extended periods of time. Moreover, maintenance considerations for such machine monitors dictate that the monitor should be easy to install and replace, and that the monitor's electronics, sensors, and batteries (when applicable) be easily accessed. Provisions should also be incorporated into the monitor to enable maintenance personnel to easily download machine data stored by the monitor and to upload new programming to the monitor when needed.
Attempts have been made in the prior art to provide enclosures for protecting various instruments and electronic devices. However, none of the enclosures resulting from these attempts are suitable for housing machine monitoring sensors and associated electronics of the type herein described.
For example, U.S. Pat. No. 4,315,432 to Newton describes a canister for housing an instrument such as a differential pressure transmitter for measuring liquid level in a tank. The canister consists of two housings which are threaded onto a support ring to form a housing within which the instrument is mounted. The support ring functions as the main structural member and includes an outer bracket for mounting the canister to a wall or tank, and an inner bracket for mounting the instrument within the canister. Various penetrations are provided in the sides of the canister for routing electrical wires and fluid conduits to the instrument.
U.S. Pat. No. 5,503,271 to Lynch describes an electric meter case for enclosing and protecting an electric meter during storage or transport. The case includes a base onto which a cover is threadably attached. An inwardly extending ring on both the base and cover encloses the meter's flange so that when the cover and base are screwed together, the cover, base, and meter are all locked.
Such prior art devices are unfit for use as machine monitor enclosures for several reasons. First, the prior art generally does not provide a structural enclosure which enables good sensory coupling between sensors and a machine. First, installation provisions for devices such as the Newton canister are very cumbersome. Installation of the Newton canister is essentially a three-part process where the support ring is first attached, then the upper and lower housing elements are each threaded onto the support ring. Often, it is desirable to monitor a particular machine for a period of time and then relocate the monitor to another machine, or perhaps to a different test point on the same machine. To enhance portability, the mounting provisions should enable the monitor to be easily engaged and disengaged from the machine. Second, the prior art does not teach a simple, easy means for accessing equipment within the housing. Ease of access (and installation) is particularly important when the monitor is mounted in a location which is difficult to reach. Third, the prior art fails to include provisions within the enclosure for securing electronics such as circuit boards, batteries, and sensors. Fourth, there are no provisions in the prior art devices for communicating with electronics located within the enclosure.
What is needed, therefore, is a structural enclosure capable of housing electronics and sensors for monitoring the status of a machine. The enclosure should be particularly adapted to be easily installed on and removed from a machine, it should enable easy access to the electronics and sensors located within the enclosure, it should be rugged and capable of affording suitable protection for internal electronics and sensors from harsh environmental elements, and it should include provisions to enable communication between internal electronics and external devices.